Plate clamp



June 24, 1930.

c. w. LHARROLD PLATE CLAMP Filed oct. 22. 1927 IQ* I I n vs n Por, CHAR/.5s WH /r/raa.

x www MN NK NNH h. NN

Patented June 24, 1939 r yPrice CHARLES W. HARROLD, OE CLEVELAND, OHIO, ASSIGNOR TO HARRISSEYBOLD-POTTER COMPANY', OF CLEVELAND, OHO, A CGRPORATION OF DELAWARE PLATE CLAME Application filed October 22, 1927. Serial No. 227,882.

My invention relates to improved clamping devices for securing flexible sheets vor plates in even and firm contact with a suitable support, and is particularly adapted for securing the Zinc plates to the cylinders in offset printing presses.

The objects of my invention are, among other things, to provide a simple and novel clamp mechanism for such printing plates which shall be convenient to operate and which shall strain and hold the plate wrapped about the cylinder surface with a uniform tension so as to avoid any wrinkles or unevenness on the surface of the iieXible plate whereby accurate printing is ensured. A further object of my invention is the provision of an improved plate-clainp which will embody the desired features of simplicity, efficiency. and durability', and which willy enable the flexible plates t-o be clamped to the cylinders and released therefrom easily and quickly by a single movement of a bar or rod, and also to reduce the likelihood of derangeinent or mutilation of the plates to a minimum in such operations.

Vith these and other objects in view, my invention comprises the construction, combination and arrangement of the various parts hereinafter described, and then particularly pointed out in the'appended claims.

In the accompanying drawings, Fig. 1 is a front elevation of a printing-press cylinder equipped with my improved plate-clamp in a preferred form;

Fig. 2 is a cross-section on the line 2 2 of Fig` l; j

Fig.V 3 is an enlarged plan or face view showing the clamp in operative position;

Fig. 4 is a sectional view on the line l-- of Fig. 3;

Fig. 5 is a cross-section on the line 5-5 of Fig. 3 showing the clamp in open position;

Fig. 6 is a cross-section on the line 6-6 of Fig. 3; and f Fig. 7 is a cross-section on the line 7 -7 of Fig. 3, showing the clampin closed position. Fig. 7a is a detail cross-section of a modified form of plate-clamp. i

Similar numerals refer to similar parts throughout the several figures. f

Referring more particularly to Figs. 1 and 2, the printing-press cylinder 8 is cut away along its top portion to provide the longitudinal pocket 9 to contain the rear clamps and their supporting mechanism 10 hereinafter to be described in detail. At the front edge of the cylinder 8 a similar longitudinal pooket 11 is formed to contain the front clamps and their supporting and adjusting members 12 (Fig. 2). The flexible plate 13 for the cyl'- inder 8 is first grippedby the several jaws of the front clamps and then is wrapped around the cylinder 8 and clamped by the several jaws of the rear clamps; suoli plate 13 is then pulled tightv around the peripheral surface of the cylinder 8 by manipulating the rear clamps contained in the top portion pocket 9, an-d thereafter the final adjustments are made through' manipulation of the adjustment screws hereinafter to be described.

The rear clamps and their supporting mechanism comprise the shelf portion 14 (three such shelves being shown in alinement in Fig. 1 and in detail in Fig. 2), on which shelf rests the bottom jaw 15. rlfhe shelf 14 and bottom jaw 15 may be secured together by bolts 16 as shown in Fig. 1. The shelf 14 has a pair of downwardly extending arms 17 j-ournalled on the cross-shaft 18 carried in bearings 19 securedto the cylinder ends 20 'and 21. Between the arms 17 and beneath the shelf 14 is a tapped boss 22 intoI which is screw-threaded the adjusting screw 23, vthe tip 24 of which screw 23 bears on the plate25 secured to the cylinder 8l (Figs. 1 and 2). Upon turning the screw 23m the boss 22 the shelf 14 which carries the rear clamps af'- fixed to the plate 13 may be swung about the cross-shaft 18 as an axis whereby'the plate 13 may be tightened and heldin firm Contact with the surface of the cylinder 8.. v

Referring to the front clamps and their supporting and adjusting members 12 contained in the pocket `11, thev bottom clamp jaw 26 is in the form of a fiat plate (Fig. ll) which extends'throughout the length of the cylinder 8 and isaffiiied thereto by the bolts 27 passing through the holes28 (Figs. 1 and 4). The bottom clamp jaw 26 is preferably of the same width as the bottomjaws 15 for the rear clamps. Arranged on the underside of clamp plate 26 are a series of spaced-apart blocks 29 secured to the plate 26 @by screws 30 (Figs. 3 and 4). The blocks 29 have screwthreaded bores 31 (Figs. 2, 6 and 7) through which the adjusting screws 32 are operated to raise and lower the plate 26 in the pocket 11 together with the front clamps to make the final adjustment of the plate 13 around the cylinder 8. The top side of the plate 26 carries spaced-apart studs 33 which carry coil springs 34 tensioned against the cylinder 8 as shown in Figs. 1 and 2.

The construction, arrangement and adjustment of the respective setsI of front and rear clamps which seize the two ends ofthe flexible plate 13 are similar to each other so that a description of but one set of clamps is suicient-` Referring to the detail Figures 3-7, the bottom clamp jaw 15 or plate 26 has near its top edge along its outer surface the semi-circular depression or groove 35 (Figs. 2, 5-7) which forms a bearing for the camrod 36 which rocks the upper jaw 37 of the clamp upon rotation ofthe rod 36, the jaw 37 coacting with the bottom jaws 15 and 26 to hold the ends of the plate 13 as shown in Fig. 2. Between the upper'jaw 37 and the lower or bottom jaws 15 or 26 are secured coil-springs 33 (Fig. 6) which normally hold the jaws separated, as shown in Fig. 5. The upper jaws 37 are pinned to the lower jaws 15 and 26 by the pivot bars 39 operating in the curved pockets 40, such bars 39 being adjustably held in position by the capscrews 41 tapped into the bars 39 (Figs. 4, 5 and 6). This arrangement enables the upper and lower jaws of the various clamps to be adjusted for the proper grip on thick -or thin plates for the cylinders bymanipulating the cap-screws 41 to vary therposition of the pivot bars 39 bearing on the pockets 40.

To rotate the cam-rod 36, the spaced-apart disks 42 are fastened thereto each having a radially-disposed hole 43 drilled therein to contain the removable handle-bar 44 which acts in place of the usual wrench to shift the clamping jaws 15, 26 and 37 from their open (Fig. 6) position to their closed, plategripping (Fig. 7) positionfand vice versa. After making the plate-seizure through the closing of the jaws of the twoA sets of clamps, the bar 44 is withdrawn from the disks 42, and the straining and adjustment of the plate 13 on the-cylinder 8 are made by turning the adjusting screws 23 and 32 as hereinbefore described. j

)Vhile the plate-clamps have been described in connection with the mounting of the printing plates 13 on the cylinder 8, it will be evident that my improved construction is equally well adapted for fastening the rubber offset blanket to the transfer cylinder.

In Fig.V 7 a l have shown ka modified form of plate-clamping mechanism in which the toggle-members 45 and 46 are transversely disposed between the clamp jaws 15 or 26 and the clamp jaw 37, the toggle-member 45 being affixed to one of the disks 42 which is -actuated by the removable handle-bar 44 as previously described, whereby the coacting clampaws may grip or release the plate 13 as the toggle is made or broken by rotating the disk 42. For the front clamps shown in Figs. 1 and 3, the cam-rod 36 may advantageously be a continuous bar contacting along the full width of the clamps to secure a firm and uniform grip on the plate 13.

My invention is not to be limited to the precise details of construction shown, as various changes and modifications may be madeV therein without departing from the scope of the invention or sacrificing the advantages derived from its use.

I claim as my invention:

1. A plate-clamp for positioning a flexible plate on its support comprising coacting clamping members to grip the plate and cam means between and bearing on each of said members throughout their operative width to actuate the latter in either direction.

2. A plate-clamp for positioning a flexible plate on its support comprising coacting clamping men bers to grip the plate, cam means between and bearing on each of said members throughout their operative width, and means to rotate said cam means in both directions to grip and release said plate.

3. A plate-clamp for positioning a flexible plate on its support comprising coacting clamping members to grip the plate, means normally holding said members in openposition, and cam meansV between and bearing on each of said members throughout their operative width to actuate the latter to grip the plate.

4. A plate-clamp for positioning a flexible plate on its support comprising kcoacting clamping members to grip' the plate, a spring normally holding said members in open position, and cam means between andV bearing on each of said members throughout their operative width to actuate the latter to grip the plate and compress said spring.

5. A plate-clamp for positioninga flexible plate on its support comprising a fixed under jaw, an upper jaw pivotally mounted on said fixed jaw, and a rotatable cam-rod between and bearing on each of said jaws throughout its operative width to grip and release same` onand from the plate.

6. A plate-clamp for positioning a flexible plate on its support comprising a fixed under jaw, an upper jaw pivotally mounted on said fixed jaw, and a rotatable cam-rod transversely disposed between and bearing on each of said jaws to grip and release same on and Y from the plate.

v7. A plate-clamp for positioning a flexible Y plate on its support comprising coacting clamping members to grip the plate, expansible means between and bearing on said menibers throughout their operative width, and an adjustable pivot mounting for said members whereby the latter may grip plates of varying thickness.

8. A plate-'clamp for positioning a flexible plate on its support comprising a fixed under jaw, a coacting upper jaw pivotally mounted on said under jaw, a spring normally holding said jaws in open position, and cam means directly bearing on said jaws substantially throughout their operative width to close same against the plate and spring.

9. A plate-clamp for positioning a flexible plate on its support comprising a fixed under j aw, a coacting upper aw pivotally mounted on said under jaw, a spring normally hold ing said jaws in open position, means for adjusting said pivot mounting to vary the relative positions of said jaws, and cam means directly bearing on said jaws to close same against the plate and spring.

10. In combination, a printing cylinder having a gap to receive a printing plate end, a plurality of clamps for holding the plate on the cylinder, and a single mechanism arranged between and bearing on each of said clamps for operating said clamps in unison.

11. In combination, a printing cylinder having a gap to receive a printing plate end, a plurality of clamps for holding the plate on the cylinder, and a single transversely-olisposed cam rod arranged between and bearing on each of said clamps for operating said clamps in unison.

12. In combination, a printing cylinder having a gap to receive a flexible printing plate end, a plurality of clamps for gripping said plate end comprising a fixed under jaw and a plurality of coacting pivotally mounted upper jaws, and a single cam means for operating said upper jaws in unison to grip the plate.

13. A plate-clamp for positioning a flexible plate on a printing-press cylinder comprising coacting clamping members to grip the plate, cam means between and bearing on each of said members throughout their operative width to close the latter on the plate, and means for shifting said clamp laterally to adjust said plate to the cylinder.

14. A plate-clamp for positioning a ilexible plate on a printing-press cylinder having a gap comprising coacting clamping members to grip the plate, cam means between and bearing on each of said members throughout their operative width to close the latter on the plate, and means within said cylinder gap for shifting said clamp laterally-to adjust said plate to the cylinder.

15. A plate-clamp for positioning a flexible plate on its support comprising coacting clamping members and rotatable means disposed between and bearing on each of said members throughout their operative width to exert upon rotation a transverse pressure on the latter to grip the plate.

16. In combination, a printing cylinder having a gap to receive a printing plate end, a plurality of clamps for holding the plate on the cylinder, and rotatable means disposed between and bearing on each of said clamps throughout its operative width to exert upon rotation a uniform transverse pressure on each clamp to grip the plate in unison.

17. In combination, a printing cylinder having a gap to receive a printing plate end, a plurality of clamps for holding the plate on the cylinder, and a single mechanism ar` ranged between and directly bearing on said clamps throughout their operative width to actuate each with a uniform pressure on the plate.

18. In combination, a printing cylinder having a gap to receive a printing plate end, a plurality of clamps for holding the plate on the cylinder, and a single cam-member arranged between and directly bearing on said clamps throughout their operative width simultaneously to actuate each with a uniform pressure on the plate.

19. A plate-clamp for positioning a ilexible plate on its support comprising coacting clamping members to grip the plate and expansible means between and bearing on each of said members throughout its operative width to close the latter on the plate.

20. A plate-clamp for positioning a ilexible plate on its support comprising coacting clamping members to grip the plate, an adjustable pivot mounting' for said members, and expansible means between and bearing on each of said members throughout its operative width to close the latter on the plate.

CHARLES W. HARROLD.

llo 

